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<title>Classification of Thin plates</title>

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<h2 id="toc_0.1">Classifications of thin plates</h2>

<p>
<strong>Defination 1</strong> : Thin plates are initially flat structural memebers bounded by two parallel
planes, called <em>faces</em>, and a cylindrical surface, called an <em>eage of boundary</em>.
</p>

<p>
<strong>Defination 2</strong>: The distance between the plane faces is called the
 <em>thickness</em>$(h)$ of the plate.
</p>

<p>
Plates may be classified into three groups according to the ratio $a/h$, where
$a$ is a typical dimension of plates in a plane and $h$ is a plate thickness.
These groups are 
</p>

<ol>
<li>
Thick plates: the ratios $a/h \le 8 \ldots 10$. The analysis of such bodies
	using the general equations of three-dimensional elasticity.
</li>
<li>
Membranes: the ratios $a/h \ge 80 \ldots 100$. 
</li>
<li>
Thin plates: the ratio $8 \ldots 10 \le a/h \ge 80 \ldots 100$.
</li>
</ol>

<p>
Thin plate may also be subdivided into two different classes by the ratio $w/h$ 
which is the ratio of the maximum deflection of the plate to its
thickness.
</p>

<p>
The first class is <em>Stiff Plates</em> : A plate can be classified as a stiff 
palte if $w/h \le 0.2$.
</p>

<p>
The second class is <em>Flexible plates</em>: if the plate deflections are
beyond a certain level, $w/h \ge 0.3$, then the lateral deflections
will be accompanied by stretching of the middle seuface.
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